int n = 8;
        char K[n + 1];
        unsigned char key[n][256];

        for (j = 0; j < n; j++)
                for (i = 0; i < 256; i++)
                        key[j][i] = i;
        for (i = 0; i < c; i++)
                for (j = 0; j < l[i]; j++)
                        key[j % n][s[i][j]] = 0;
        for (k = 0; k < n; k++) {
                for (i = 0, j = 0; i < 256; i++)
                        if (isprint(key[k][i]))
                                key[k][j++] = key[k][i];
                if (j < 1) {
                        printf("Failed at %d\n", k);
                        return 2;
                }
                K[k] = key[k][random() % j];
        }
        K[k] = 0;
        printf("KEY IS %s\n", K);

        for (a = 1; a < n; a++)
        for (b = 1; b < n; b++)
        for (c = 1; c < n; c++) {
                if (gcd(a * b, n) != 1)
                        continue;
                x = 0;
                y = b;
                bzero(o, sizeof(o));
                for (j = 0; j < n; j++) {
                        x = (a * c + y) % n;
                        y = (y + b) % n;
                        o[x]++;
                }
                for (j = 0; j < n; j++)
                        assert(o[j] == 1);
        }